The present invention relates to a metal gasket with flanges around holes for providing resilient surface pressure at a narrow intermediate area between the holes.
In a metal gasket or a metal laminate gasket, a plurality of holes, such as cylinder bores and fluid holes, is formed. In order to securely seal around the holes, beads and/or flanges (turned portion) are formed around the holes. The bead means a projection extending outwardly from a metal plate or a stepped portion to provide a surface pressure thereat. On the other hand, the flange means a turned or overlapped portion around a hole. When the gasket is situated between a cylinder head and a cylinder block, the beads and/or flanges are compressed to securely seal around the holes.
In case the flanges or turning portions are formed around the holes, the flanges are located on the same side of the metal plate. When the gasket is tightened between the cylinder head and the cylinder block, the flanges around the holes are compressed to provide high surface pressure. However, since the flange does not provide resiliency by itself, surface pressure formed by resiliency can not be formed. Also, equal surface pressure may not be formed throughout the entire area of the flange.
On the other hand, in case the bead is formed around the hole, when the gasket is tightened between the cylinder head and the cylinder block, the bead is compressed to provide surface pressure thereat. In this case, if the surface pressure of the bead is strong, the cylinder bore may deform to cause a serious problem for the engine.
Therefore, there have been proposed gaskets having a flange and a bead to obviate the deformation problem, wherein the bead is formed outside the flange. The combination of the flange and bead can avoid the deformation problem, but in case the distance between the bores is not sufficient, it is not possible to provide the flange and the bead around a bore.
In view of the foregoing, the present invention has been made, and an object of the invention is to provide a metal gasket wherein a surface pressure for sealing is formed at a narrow portion between bores.
Another object of the invention is to provide a metal gasket as stated above, wherein even if a gap exists in sealing portions around the bores, the gasket can securely seal around the bores.
A further object of the invention is to provide a metal gasket as stated above, wherein the gasket can be made thin and simple.
Further objects and advantages of the invention will be apparent from the following description of the invention.